CHICAGO (NewsNation Now) — The Chicago Teachers Union has approved a deal with the nation’s third-largest school district to get students back to class during the coronavirus pandemic, union officials announced early Wednesday.

The vote by the union’s roughly 25,000 members ends the possibility of an immediate teacher lockout or strike. The agreement follows months of negotiations — which had intensified in recent weeks — with plans that included more teacher vaccinations and metrics to allow school closures when COVID-19 infections spikes.

Votes were certified just before 12:30 a.m. Wednesday morning, NewsNation affiliate WGN reported. Some students are now set to begin in person learning starting Thursday morning.

The union said 13,681 members voted to approve the agreement and 6,585 voted against it. In a statement, the union described the agreement as the “absolute limit to which CPS was willing to go at the bargaining table to guarantee a minimum number of guardrails for any semblance of safety in schools.”

Union President Jesse Sharkey also criticized the agreement in an email to members that was released by the union.

“This plan is not what any of us deserve. Not us. Not our students. Not their families,” the email said. “The fact that CPS could not delay reopening a few short weeks to ramp up vaccinations and preparations in schools is a disgrace.”

The first wave of students, in pre-K and special education, are due back Thursday. Other students in K-8 will return in the coming weeks for limited classroom instruction. Kindergarten through 5th-grade staff would return Feb. 22, with students returning March 1. After that, 6th through 8th-grade staff would return to the buildings on March 1 with students returning March 8, WGN reported.

No plans have been set for high school students, who’ll continue with online learning.

Talks over resuming classroom instruction since going fully remote last March have been heated amid debates worldwide over reopening schools. Chicago Mayor Lori Lightfoot had warned teachers that they would be locked out of district systems if they didn’t report for duty. The union countered by threatening to strike.

Chicago Public Schools officials have insisted it is safe to have classes in person with protocols in place, like wearing face coverings and a $100 million safety plan that includes thousands of classroom air filters. District officials and Lightfoot has said remote instruction is leaving many behind, particularly Black and Latino students who make up the majority of the roughly 340,000-student district.

Under the agreement special accommodations will be made for staff who have members of the household who are medically compromised WGN reported. Vaccinations will also be offered to staff.

The union contends the district’s plans falls short in protecting teachers and that not enough students have been interested in returning to fully staff more than 600 schools. The union previously voted to defy orders to return to classes and continued teaching remotely.

Early parent surveys showed about 77,000 students were interested in returning to classes. When in-person school briefly resumed last month for special education and pre-K students, student attendance was roughly 19% of those eligible.

The Associated Press and NewsNation affiliate WGN contributed to this article.